Method for detecting full charge state of battery

• US 6,311,080 B1
• Filed: 01/26/1999
• Issued: 10/30/2001
• Est. Priority Date: 01/29/1998
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: OKI Electric Industry Company Limited
• Inventors: Mochida, Muneaki
• Primary Examiner(s): Vo, Nguyen T.
• Assistant Examiner(s): APPIAH, CHARLES NANA
• Application Number:
  US09/236,625
• Time in Patent Office: 1,008 Days
• Field of Search: 455/573, 455/572, 455/574, 455/343, 320/137, 324/427, 324/433, 324/428
• US Class Current: 455/573
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition

Abstract

A method for detecting a full charge state has the steps of obtaining a first data series including first to N-th data items, the first to N-th data items of the first data series corresponding to battery voltages measured at first sampling intervals during a first sampling time period, respectively; and obtaining a second data series including first to N-th data items, the first to N-th data items of the second data series corresponding to battery voltages measured at second sampling intervals during a second sampling time period, respectively. A predetermined time delay is provided between a beginning of the first sampling time period and a beginning of the second sampling time period, and the second sampling intervals are the same as the first sampling intervals. The method has the further steps of comparing an i-th data item of the first data series and an i-th data item of the second data series (i=1, 2, . . . , N) to obtain a number of times that the i-th data item of the second data series is smaller than the i-th data item of the first data series; and judging whether or not the battery has reached the full charge state on the basis of a ratio of the number of times to N.

Claims

1. A method for detecting a full charge state of a battery during a charging operation, comprising the steps of:

obtaining a first data series including first to N-th data items, where N is a predetermined positive integer not less than 2, the first to N-th data items of the first data series corresponding to battery voltages measured at first sampling intervals during a first sampling time period, respectively;

obtaining a second data series including first to N-th data items, the first to N-th data items of the second data series corresponding to battery voltages measured at second sampling intervals during a second sampling time period, respectively, a predetermined time delay being provided between a beginning of the first sampling time period and a beginning of the second sampling time period, the second sampling intervals being the same as the first sampling intervals;

comparing an i-th data item of the first data series and an i-th data item of the second data series to obtain a number of times that the i-th data item of the second data series is smaller than the i-th data item of the first data series, where i=1, 2, . . . , N; and

judging whether or not the battery has reached the full charge state on the basis of a ratio of the number of times to N.

2. A method of claim 1, wherein the first sampling intervals are even intervals, and the second sampling intervals are even intervals.

3. A method of claim 1, wherein the first sampling intervals are uneven intervals, and the second sampling intervals are uneven intervals.

4. A method of claim 1, wherein the second sampling time period begins after an end of the first sampling time period.

5. A method of claim 1, wherein the second sampling time period begins during the first sampling time period.

6. A method of claim 1, wherein, in said step of comparing, the i-th data item of the second data series is the (i+j)-th data item of the first data series, where j is a predetermined positive integer not more than N−

1.

7. A device for detecting a full charge state of a battery during a charging operation, comprising:

a measuring circuit for measuring a battery voltage; and

a controller for controlling said measuring circuit;

wherein said controller obtains a first data series including first to N-th data items, where N is a predetermined positive integer not less than 2, the first to N-th data items of the first data series corresponding to battery voltages measured by said measuring circuit at first sampling intervals during a first sampling time period, respectively;

said controller obtains a second data series including first to N-th data items, the first to N-th data items of the second data series corresponding to battery voltages measured by said measuring circuit at second sampling intervals during a second sampling time period, respectively, a predetermined time delay being provided between a beginning of the first sampling time period and a beginning of the second sampling time period, the second sampling intervals being the same as the first sampling intervals; and

said controller compares an i-th data item of the first data series and an i-th data item of the second data series to obtain a number of times that the i-th data item of the second data series is smaller than the i-th data item of the first data series, where i=1, 2, . . . , N, and judges whether or not the battery has reached the full charge state on the basis of a ratio of the number of times to N.

8. A device of claim 7, wherein the first sampling intervals are even intervals, and the second sampling intervals even intervals.

9. A device of claim 7, wherein the first sampling intervals are uneven intervals, and the second sampling intervals uneven intervals.

10. A device of claim 7, wherein the second sampling time period begins after an end of the first sampling time period.

11. A device of claim 7, wherein the second sampling time period begins during the first sampling time period.

12. A device of claim 7, wherein the i-th data item of the second data series is the (i+j)-th data item of the first data series, where j is a predetermined positive integer not more than N−

1.

13. A cellular telephone comprising:

a measuring circuit for measuring a battery voltage of a battery; and

a controller for controlling said measuring circuit and a charging circuit of a charger for the cellular telephone;

wherein said controller obtains a first data series including first to N-th data items, where N is a predetermined positive integer not less than 2, the first to N-th data items of the first data series corresponding to battery voltages measured by said measuring circuit at first sampling intervals during a first sampling time period, respectively;

said controller obtains a second data series including first to N-th data items, the first to N-th data items of the second data series corresponding to battery voltages measured by said measuring circuit at second sampling intervals during a second sampling time period, respectively, a predetermined time delay being provided between a beginning of the first sampling time period and a beginning of the second sampling time period, the second sampling intervals being the same as the first sampling intervals;

said controller compares an i-th data item of the first data series and an i-th data item of the second data series to obtain a number of times that the i-th data item of the second data series is smaller than the i-th data item of the first data series, where i=1, 2, . . . , N, and judges whether or not the battery has reached the full charge state on the basis of a ratio of the number of times to N; and

said controller causes the charging circuit of the charger to stop charging when said controller judges that the battery has reached the full charge state.

14. A cellular telephone of claim 13, wherein the first sampling intervals are even intervals, and the second sampling intervals even intervals.

15. A cellular telephone of claim 13, wherein the first sampling intervals are uneven intervals, and the second sampling intervals uneven intervals.

16. A cellular telephone of claim 13, wherein the second sampling time period begins after an end of the first sampling time period.

17. A cellular telephone of claim 13, wherein the second sampling time period begins during the first sampling time period.

18. A cellular telephone of claim 13, wherein the i-th data item of the second data series is the (i+j)-th data item of the first data series, where j is a predetermined positive integer not more than N−

1.